Vehicle wheel vibration monitoring system

ABSTRACT

A vibration monitor is mounted on axles of a truck for monitoring vibrations in the axles and wheels of the truck which may indicate some type of failure associated with the wheels. The monitor includes a pair of pneumatic sensors mounted on the axles which are connected to a control box for disabling the truck. The control box is arranged to vent the air brake circuit of the truck for applying the brakes of the truck if the control box receives a vibration signal from the sensors having a magnitude which exceeds an acceleration threshold and a duration which exceeds a time threshold.

FIELD OF THE INVENTION

This invention relates to a vibration monitoring system for use in amotor vehicle and more particularly to a system for stopping the vehiclein response to a prescribed condition sensed by the system.

BACKGROUND

The use of large trucks for towing cargo trailers is common fortransporting goods along various roadways. The trucks tend to travellong distances and are thus subject to various types of failure due totheir repeated use. It has been known for trailer tires to come loosefrom their hubs and for tires be shredded once a small rupture hasoccurred. A released wheel or tire carcass on the road is a major roadhazard.

Canadian Patents Applications 2,199,649 and 2,226,829 describe amonitoring device for detecting failures associated with the wheels oftrucks and trailers. The device comprises individual axle spindlesensors and an alarm for alerting a driver of the truck when the sensorsdetect a vibration on the wheels or axles which indicates a possiblefailure. While the device senses vibrations which may indicate apotential failure, a driver may ignore, fail to notice or even disablethe alarm indicator.

SUMMARY

According to the present invention there is provided a vibration monitorfor use in monitoring vibrations on a wheel of a vehicle, the monitorcomprising:

sensor means associated with the wheel for producing a vibration signalin response to a vibration comprising repeated accelerations acting onthe wheel over an elapsed period of time; and

disabling means for disabling the vehicle in response to receipt of avibration signal from the sensor means which exceeds a prescribedvibration condition.

The use of the vibration monitor mounted on a truck for monitoringvibrations in the wheels of the truck reduces the risk of a dangerousaccident resulting from a failure to one of the wheels or the axles ofthe truck. The disabling means ensures that the driver will be alertedand aware of possible failures by eliminating the risk of a driverignoring or not noticing an indicator connected to the sensor means inplace of the disabling means. The active feedback of the disabling meansfor halting the truck movement provides a greater guarantee of safety toother people on the road as opposed to relying upon the responsibilityof the drivers of trucks on the road when the vibration monitor is notused.

The prescribed vibration condition preferably comprises an accelerationthreshold and a time threshold such that a magnitude of the vibrationmust exceed the acceleration threshold and a duration of the vibrationmust exceed the time threshold in order for the disabling means todisable the vehicle.

The acceleration threshold is preferably adjustable over a range ofmagnitudes while the time threshold is preferably adjustable over arange of time limits.

The sensor means may comprise a pneumatic sensor such that the vibrationsignal is transmitted through a sensor line in the form of a variationin air pressure.

The disabling means preferably comprises a control element coupled toair brakes of the vehicle such that air pressure of the brakes is ventedfor applying the brakes when the control element receives the vibrationsignal.

The disabling means may alternatively comprise a control element coupleda throttle of the vehicle such that the vehicle is disabled when thecontrol element receives the vibration signal.

An indicator may be coupled to the sensor line for indicating when thedisabling means have been activated.

Preferably there is provided a reset element coupled to the disablingmeans such that when the vehicle is disabled, the vehicle remainsdisabled until the reset element is activated.

The reset element may comprise a manual switch coupled to the disablingmeans or a remote switch coupled to the disabling means such that anoperator of the vehicle can reset the disabling means remotely.

The sensor means are preferably mounted on respective axles of thevehicle for sensing vibrations in the wheels and the axles of thevehicle.

One particular advantageous embodiment includes a wireless transmitterfor each sensor and a receiver at the control for the disabling means.Instead of pneumatics, the sensor means may comprise an electricalsensor such that the vibration signal comprises an electrical signalwhich is representative of a vibration acting on the wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which illustrate an exemplary embodimentof the present invention:

FIG. 1 is a top plan view of a pair of truck axles with a schematic ofthe vibration monitor connected thereto.

FIG. 2 is a schematic showing internal components of the control box ofFIG. 1.

FIG. 3 is a top plan view of a pair of truck axles with a schematic of asecond embodiment of the vibration monitor connected thereto.

DETAILED DESCRIPTION

Referring to the accompanying drawings, there is illustrated a vibrationmonitor generally indicated by reference numeral 10. The vibrationmonitor 10 is intended for use in monitoring vibrations in the wheels 12and axles 14 of a conventional truck or trailer. Monitoring vibrationsin the wheels and axles provides a warning to a truck driver that suchfailures as loose tires, shredded tires or cracked and broken shafts andbearings may be present before the failure causes further damage. Themonitor 10 is particularly suited for a truck which uses air brakescontrolled by a main supply tank 16 of pressurised air. The pressure ofair in the tank is controlled by a compressor 18 in a conventionalarrangement.

The monitor 10 includes a vibration sensor 20 which mounts on each axle14 of the truck spaced between the corresponding wheels 12 as well as onthe axles of any associated trailer connected to the truck. The sensor20 is a commercial available sensor known as a Model 4109 Vibro-guardvalve manufactured by Instrument and Control Service Company Inc. ofLake Villa, Ill. The sensor 20 is a two way acceleration sensing valve.Under normal conditions the valve of sensor 20 is closed, however whenvibrations or shocks exceed a prescribed magnitude, the valve trips openand vents. The prescribed magnitude is adjusted as desired once thesensor 20 has been installed. A microswitch is included in the sensor 20for producing an electrical signal when the valve is tripped for usewith an electrical system as desired.

The sensors 20 are connected in series along a sensor line 22. Thesensor line 22 connects the sensors 20 to a control box 24, the internalcomponents of which will be described in further detail below. Thesensor line 22 is connected at a venting end 26 to terminal B2 of thecontrol box 24 and connected at a reset end 28 to terminal B3 of thecontrol box.

A main pressure supply line 30 is connected to terminal B1 of thecontrol box and supplies pressurised air to the control box. The supplyline 30 is connected directly to the main supply tank 16. The air in thesupply tank is passed through an air dryer for use in colder climates toremove any moisture which could affect the functioning of the valves.

A remote reset line 32 is connected to terminal B4 of the control box ata first end. A second end of the reset line 32 is connected to a remotesupply of pressurised air such that activation of a remote reset switchwill send a reset signal in the form of a flow of pressurised airthrough the reset line 32 and into the control box via terminal B4. Thereset signal is also generated by activating a manual reset switch 34 onthe control box 24 which allows the flow of pressurised air forresetting the control box to be diverted from the main supply line 30instead of through the reset line 32 as described in further detailbelow.

A control line 36 connects terminal B7 of the control box to a junctionbox 38. The junction box 38 forms a part of the air brake circuit of thetruck such that venting the control line 36 will vent the air pressurein the brake circuit such that the brakes of the vehicle are applied. Avent line 40 is connected to the terminal B5 of the control box forventing the control line 36 when a vibration condition is sensed by thecontrol box. The vibration condition comprises a vibration of repeatedaccelerations which has acted on one of the wheels or axles of thetruck. The vibration must be of sufficient magnitude as determined bythe sensor 20 and of sufficient duration as determined by the controlbox 24 to exceed prescribed a magnitude and duration in order for thecontrol box to determine a vibration condition for venting the controlline 36.

The inner components of the control box 24 are shown in greater detailin FIG. 2 of the drawings. The terminal B1 receives the main supply line30 for supplying pressurised air to the system within the control box24. A pressure regulator 50 is located adjacent the terminal B1 forregulating the air pressure.

The manual reset switch 34 is connected to the output of the regulator50 such that depressing the switch will open the line for allowing thepressurised air to pass. This supply of pressurised air from the manualreset switch acts to reset the system to an equilibrium in a nonvibration condition.

A first control switch 52 includes an upper latch 54 connected at anoutput to port 4 of the switch, the latch being movable at an inputbetween ports 3 and 5 of the switch wherein port 3 is sealed shut. Thefirst control switch 52 also includes a lower latch 56 connected at anoutput to port 2 of the switch and is movable at an input between ports1 and 3 of the switch. The first control switch 52 includes a firstpressure chamber at an upper end A and a second pressure chamber at alower end B such that changes in the relative pressure between ends Aand B will effectively displace the upper and lower latches 54, 56between the respective inputs in a direction away from the greaterpressure at either end A or end B of the switch.

The first control switch 52 is connected at end A to the output of theregulator 50 through a flow restrictor 58 and is also connected to theoutput of the regulator 50 at port 1.

A second control switch 60 includes a single latch 62 connected at anoutput to port 2 of the switch, the latch being movable at an inputbetween ports 1 and 3 of the switch. The single latch 62 is controlledsimilarly to the first control switch by respective pressure chambers atends A and B of the second control switch 60. The end A of the secondcontrol switch 60 is connected to port 2 of the first control switch 60for receiving pressurised air therethrough from the regulator when thelower latch 56 is connected to port 1. Port 3 of the second controlswitch is connected to the output of the regulator for receivingpressurised air therefrom.

A third control switch 64 includes an upper latch 66 connected at anoutput to port 4 of the switch, the latch being movable at an inputbetween ports 3 and 5 of the switch. The third control switch 64 alsoincludes a lower latch 68 connected at an output to port 2 of theswitch, the latch being movable at an input between ports 1 and 3 of theswitch. The latches 66, 68 are controlled similarly to the first controlswitch by respective pressure chambers at ends A and B of the thirdcontrol switch 64. The third control switch 64 is connected to theoutput of the regulator 50 at end A through a flow restrictor 70 and atport 3 through a check valve 72.

Terminal B2 of the control box acts as a vent when one of the sensors 20is tripped. The terminal B2 is connected to end A of the first controlswitch 52. A secondary vent line 74 connects terminal B3 of the controlbox as well as port 2 of the second control switch 60 to end A of thefirst control switch 52. A check valve 76 is mounted within thesecondary vent line 74 such that the flow of pressurised air is onlypermitted to flow through the line towards the terminal B2. Terminal B3of the control box is also connected to the sensors 20 and receivespressurised air from terminal B2 when the sensor is in a non vibrationcondition such that the flow of pressurised air flows into the controlbox through terminal B3 in the form of a reset signal. The control boxwill reach an equilibrium non vibration condition if the reset signal iscontinuously transmitted from the sensors through terminal B3 and thecontrol box has not undergone a vibration condition without being reset.

The manual reset switch 34 includes a reset latch 78 which is connectedat an output to port 2 of the switch, the latch being movable at aninput being ports 1 and 3 of the switch. Port 1 of the reset switch 34is connected to the output of the regulator while port 3 is sealed shut.Port 2 of the reset switch 34 is connected to an input of a double checkvalve 80 which acts as an OR switch. The other input of the double checkvalve 80 connects to terminal B4 of the control box. In this arrangementa flow of pressurised air coming from either the terminal B4 or from theregulator 50 when the manual reset switch 34 is depressed result in theflow of pressurised air continuing through the output of the doublecheck valve 80 in the form of a reset signal.

The output of the double check valve 80 connects to port 2 of a variablethrottling valve 82 through a check valve 84 and to end B of the secondcontrol switch 60. The throttling valve 82 is connected at port 1 of thevalve to end A of the third control switch 64. The throttling valve 82is also connected at port 3 of the valve to port 4 of the third controlswitch 64 through a flow restrictor 86. Port 4 of the throttling valve82 vents to port 5 of the first control switch 52 which then ventsthrough flow restrictor 88 into the control box when the upper latch 54is connected to port 5 of the first control switch. The flow restrictor88 vents into the control box which is vented at terminal 86.

Port 2 of the third control switch 64 is connected to end A of a maincontrol switch 90. The main control switch 90 includes a single latch 92which is connected at an output to port 2 of the switch, the latch beingmovable at an input between ports 1 and 3 of the switch. Port 1 of theswitch 90 connects to terminal B7 while port 2 of the switch connects toterminal B5 such that the switch interrupts the venting of the brakecircuit of the truck. The latch 92 is urged towards port 3 by a spring94 for preventing venting of the control line 36. End A of the maincontrol switch includes a pressure chamber for urging the latch 92towards port 1 when a flow of pressurised air is received from port 2 ofthe third control switch for venting the control line 36 when avibration condition is sensed.

End A of the main control switch 90 is also connected to an indicator96. The indicator 96 is arranged to be activated when the latch 92 ofthe main control switch 90 is displaced towards port 1 such thatactivation of the indicator indicates when the control line 36 is beingvented. The indicator 96 is mounted in a visible location such that itis clear to the operator of the truck that a vibration condition hasoccurred.

When the monitor 10 is mounted on a truck in use, the control switchesare normally oriented as shown in FIG. 2 in the non vibration conditionfor normal operation of the brakes of the vehicle. If the sensors 20mounted on the wheel axles senses a vibration of repeated accelerationswhich exceeds a predetermined acceleration threshold of the sensors inone of the wheels or axles, the sensor line 22 will begin to vent andcontinue to vent as long as the sensors 20 are being subjected to thevibration which exceeds the acceleration threshold of the sensors.

When the sensor line 22 vents, terminal B2 on the control box vents endA of the first control switch 52 such that the upper and lower latches54, 56 are deflected towards end A. The throttling valve 82 is thusvented through the flow restrictor 88 once the upper latch 54 connectsto port 5 on the first control switch 52.

Once the throttling valve 82 begins venting through flow restrictor 88,end A of the third control switch 64 is slowly vented, while theregulator partially maintains the pressure at end A of the third controlswitch 64 through the flow restrictor 70. The amount of time required tovent end A of the third control switch 64 is determined by thedifference between the venting action of the throttling valve 82 and theflow of pressurised air passing through the flow restrictor 70. Thisamount of time required to vent end A of the third control switch 64 isthe time limit threshold of the control box. The time limit threshold isthe amount of time required for one of the sensors to be exceeding itsrespective acceleration threshold before a vibration condition isdetermined and the control line is vented.

The time limit threshold is adjustable within a range of time constantsby adjusting the throttling valve 82 such that the flow of air beingvented therethrough is adjusted.

If the sensors 20 are vented for a period of time which is less than thetime limit threshold, the pressure at end A of the first control switch52 will be restored for cutting off the venting action through flowrestrictor 88 before the third control switch is deflected upward suchthat the control line is not vented.

If the sensors 20 are vented for a period of time which exceeds the timelimit threshold, the pressure at end A of the first control switch 52will be lost for venting the throttling valve 82 through flow restrictor88. Venting the throttling valve 82 will result in a pressure loss atend A of the third control switch 64 such that the upper and lowerlatches 66, 68 are deflected upward for supplying pressurised air to endA of the main control switch 90. The control line 36 will thus be ventedas the latch 92 of the main control switch is deflected downward whilethe control box remains in equilibrium in a vibration condition. Ventingthe control line 36 will result in a loss of air pressure in the brakecircuit for disabling the truck by partially or fully applying thebrakes of the truck.

The latch 92 of the main control switch 90 remains deflected downwardfor venting the control line 36 until the control box is reset. Thecontrol box is reset by producing the reset signal via the remote resetline 32 or by using the manual reset switch 34. In either case, thereset signal will provide pressurised air to end B of the second controlswitch 60 for deflecting the latch 62 upward such that the input of thelatch connects to port 3 of the switch. Once the latch 62 is deflectedupward, the output of the regulator 50 is connected therethrough to thesensor reset line 28 and to end A of the first control switch 52 throughcheck valve 76. The flow of air from the regulator will thus deflect thelatches of the first control switch 52 downward such that the throttlingvalve 82 is no longer vented. Accordingly the pressure at end A of thethird control switch 64 returns to normal for cutting off the pressureat end A of the main control switch, thus the control line 36 is nolonger vented.

In further arrangements, the junction box 38 may couple the control line36 to a system within the truck other than the brake circuit, such asthe throttle, for disabling the vehicle in response to the vibrationcondition as in the embodiment described above. Additionally, theindicator 96 may be connected to relays mounted on the respectivesensors 20 for indicating which sensor has been tripped in the event ofa vibration condition for assisting the operator in locating the failureon the truck.

Numerous sensors 20 can be mounted in series along the sensor line 22such that the sensors can be located on the axles of a trailer connectedto the truck as well as the truck itself as described above. When thesensors are mounted on the trailer, the control box can also beconnected to the brake circuit of the trailer for braking both thetrailer and the truck when a vibration is detected. The limiting factorin determining how many sensors can be connected in series is the lengthof the sensor line. Extending the length of the sensor line beyond thelimits of the system will result in an insufficient line pressure foreffectively transmitting the vibration signal.

In an alternative embodiment, as shown in FIG. 3, electronic sensors 100are mounted on the truck axles and include respective batteries 102 forpowering the sensors independently from the truck on which the sensorsare mounted.

Each sensor 100 is a remote unit having its own wireless transmitter104. The electronic sensors produce a vibration signal in response torepeated vibrations similarly to the sensors 20 of the first embodimentand remotely relay the vibration signal to an electronic control box106. The control box 106 includes a receiver 108 for receiving theremote vibration signals.

The electronic control box serves a similar purpose as the control box24 of the first embodiment for determining a vibration condition inresponse to a vibration signal from the electronic sensors which exceedsan acceleration threshold for a period of time which is longer than atime limit threshold of the control box. Once a vibration condition hasbeen determined, the control box acts in a similar manner as in thefirst embodiment to either control the brakes or the throttle of thetruck in such a manner so as to slow or stop the vehicle's movement.

The values of both the acceleration threshold and the time limitthreshold are adjustable such that the monitor responds properly tovibrations resulting from a failure while the monitor does not produce avibration condition when no failure is present.

A failsafe on the control box will trip if one of the sensor batteriesfails to ensure that the monitor is always functioning properly when thetruck is in use.

An operator interface 110 is coupled to the control box and includes anoperator indicator 112 as well as reset control buttons 114 whichfunction in response to similar conditions as in the first embodiment.

While some embodiments of the present invention have been described inthe foregoing, it is to be understood that other embodiments arepossible within the scope of the invention. The invention is to beconsidered limited solely by the scope of the appended claims.

What is claimed is:
 1. A vibration monitor for use in monitoringvibrations on a wheel of a vehicle, the monitor comprising: anacceleration sensor associated with the wheel and being arranged toproduce a vibration signal in response to and representing repeatedaccelerations acting on the wheel over an elapsed period of time; acontroller arranged to receive the vibration signal from theacceleration sensor, the controller including a time threshold and anacceleration magnitude threshold which define a prescribed vibrationcondition, the controller being arranged to determine that the vibrationsignal exceeds the prescribed vibration condition when a magnitude ofthe vibration signal exceeds the acceleration magnitude threshold and aduration of the vibration signal exceeds the time threshold; and adisabling mechanism arranged to disable the vehicle in response todetermination by the controller that the vibration signal exceeds theprescribed vibration condition.
 2. The monitor according to claim 1wherein the acceleration magnitude threshold is adjustable over a rangeof magnitudes.
 3. The monitor according to claim 1 wherein the timethreshold is adjustable over a range of time limits.
 4. The monitoraccording to claim 1 wherein the acceleration sensor comprises apneumatic sensor such that the vibration signal comprises a variation inair pressure transmitted through a sensor line between the sensor andthe controller.
 5. The monitor according to claim 4 wherein thedisabling mechanism comprises a control element coupled to air brakes ofthe vehicle such that air pressure of the brakes is vented for applyingthe brakes when the control element receives the vibration signal. 6.The monitor according to claim 4 wherein the disabling mechanismcomprises a control element coupled to a throttle of the vehicle suchthat the vehicle is disabled when the control element receives thevibration signal.
 7. The monitor according to claim 4 wherein there isprovided an indicator coupled to the sensor line for indicating when thedisabling mechanism has been activated.
 8. The monitor according toclaim 1 wherein there is provided a reset element coupled to thedisabling mechanism such that when the vehicle is disabled, the vehicleremains disabled until the reset element is activated.
 9. The monitoraccording to claim 8 wherein the reset element comprises a manual switchcoupled to the disabling mechanism.
 10. The monitor according to claim 8wherein the reset element comprises a remote switch coupled to thedisabling mechanism such that an operator of the vehicle can reset thedisabling mechanism remotely.
 11. The monitor according to claim 1wherein there is provided an indicator coupled to the disablingmechanism for indicating to an operator of the vehicle that thedisabling mechanism has been activated.
 12. The monitor according toclaim 1 wherein the acceleration sensor is mounted on respective axlesof the vehicle for sensing vibrations in the wheels and the axles of thevehicle.
 13. The monitor according to claim 1 wherein the accelerationsensor comprises an electrical sensor such that the vibration signalcomprises an electrical signal which is representative of a vibrationacting on the wheel.
 14. The monitor according to claim 1 wherein thedisabling mechanism comprises a control element coupled to brakes of thevehicle such that the brakes are applied when the control elementreceives the vibration signal.
 15. The monitor according to claim 1wherein the disabling mechanism comprises a control element coupled athrottle of the vehicle such that the vehicle is disabled when thecontrol element receives the vibration signal.
 16. A vibration monitorfor use in monitoring vibrations on a wheel of a vehicle, the monitorcomprising: an electrical acceleration sensor associated with the wheeland being arranged to sense repeated accelerations acting on the wheelin at least two different directions and produce a vibration signal inresponse to the repeated accelerations acting on the wheel over anelapsed period of time, the vibration signal comprising an electricalsignal representing the repeated accelerations acting on the wheel overthe elapsed period of time; a controller arranged to receive thevibration signal from the acceleration sensor, the controller includinga time threshold and an acceleration magnitude threshold which define aprescribed vibration condition, the controller being arranged todetermine that the vibration signal exceeds the prescribed vibrationcondition when a magnitude of the vibration signal exceeds theacceleration magnitude threshold and a duration of the vibration signalexceeds the time threshold; and a disabling mechanism arranged to engagebrakes of the vehicle in response to determination by the controllerthat the vibration signal exceeds the prescribed vibration condition soas to disable the vehicle.
 17. A vibration monitor for use in monitoringvibrations on a wheel of a vehicle, the monitor comprising: anelectrical acceleration sensor associated with the wheel and beingarranged to produce a vibration signal in response to repeatedaccelerations acting on the wheel over an elapsed period of time, thevibration signal comprising an electrical signal representing therepeated accelerations acting on the wheel over the elapsed period oftime; a controller arranged to receive the vibration signal from theacceleration sensor, the controller including a time threshold and anacceleration magnitude threshold which define a prescribed vibrationcondition, the controller being arranged to determine that the vibrationsignal exceeds the prescribed vibration condition when a magnitude ofthe vibration signal exceeds the acceleration magnitude threshold and aduration of the vibration signal exceeds the time threshold; a disablingmechanism arranged to disable the vehicle in response to determinationby the controller that the vibration signal exceeds the prescribedvibration condition; an electrical power supply arranged to supplyelectrical power to the electrical acceleration sensor; and a failsafemechanism arranged to monitor power supplied to the electricalacceleration sensor from the electrical power supply and to disable thevehicle in response to a loss of electrical power supplied to theelectrical acceleration sensor.